package com.iot08.common.utils;

import java.net.InetAddress;

/**
 * @version 1.0
 * @Description:
 * @author: Rock
 * @time: 2020/9/2 15:45
 */
public class UUIDGenerator {

    private static final int IP;
    private static short COUNTER = (short) 0;
    private static final int JVM = (int) (System.currentTimeMillis() >>> 8);

    static {
        int ipadd;
        try {
            ipadd = toInt(InetAddress.getLocalHost().getAddress());
        } catch (Exception e) {
            ipadd = 0;
        }
        IP = ipadd;
    }

    /**
     * 生成一个32位的uuid
     *
     * @time: 2020/11/4 9:28
     * @author: Rock
     * @version 1.0
     */
    public static String generate() {
        return new StringBuilder(24).append(format(getIP())).append(format(getJVM())).append(format(getHiTime()))
                .append(format(getLoTime())).append(format(getCount())).toString();

    }

    /**
     * @param intval
     * @time: 2020/11/4 9:33
     * @author: Rock
     * @version 1.0
     */
    private final static String format(int intval) {
        String formatted = Integer.toHexString(intval);
        StringBuilder buf = new StringBuilder("00000000");
        buf.replace(8 - formatted.length(), 8, formatted);
        return buf.toString();
    }

    /**
     * @param shortval
     * @time: 2020/11/4 9:33
     * @author: Rock
     * @version 1.0
     */
    private final static String format(short shortval) {
        String formatted = Integer.toHexString(shortval);
        StringBuilder buf = new StringBuilder("0000");
        buf.replace(4 - formatted.length(), 4, formatted);
        return buf.toString();
    }

    private final static int getJVM() {
        return JVM;
    }

    private final static short getCount() {
        synchronized (UUIDGenerator.class) {
            if (COUNTER < 0)
                COUNTER = 0;
            return COUNTER++;
        }
    }

    /**
     * Unique in a local network
     */
    private final static int getIP() {
        return IP;
    }

    /**
     * Unique down to millisecond
     */
    private final static short getHiTime() {
        return (short) (System.currentTimeMillis() >>> 32);
    }

    private final static int getLoTime() {
        return (int) System.currentTimeMillis();
    }

    /**
     * @param bytes
     * @time: 2020/11/4 9:33
     * @author: Rock
     * @version 1.0
     */
    private final static int toInt(byte[] bytes) {
        int result = 0;
        for (int i = 0; i < 4; i++) {
            result = (result << 8) - Byte.MIN_VALUE + (int) bytes[i];
        }
        return result;
    }

}
